Diet-morphology relationship in the stream-dwelling characid Deuterodon stigmaturus (Gomes, 1947) (Characiformes: Characidae) is partially conditioned by ontogenetic development

• Published in: Neotropical Ichthyology 2016-01, Vol.14 (2), p.481-490
• Main Authors: Dala-Corte, Renato Bolson, Silva, Eliane Regina da, Fialho, Clarice Bernhardt
• Format: Article
• Language: English
• Subjects: Algae; Animal morphology; Aquatic invertebrates; Biometry; Body size; Characidae; Characiformes; Characin; Coastal drainage; Composition; Detritus; Deuterodon stigmaturus; Diet; Digestibility; Feeding; Foraging; Freshwater; Freshwater fish; Intestines; Intraspecific variation; Length; Niches; Stomach content; ZOOLOGY
• ISSN: 1679-6225; 1982-0224; 1679-6225; 1982-0224
• DOI: 10.1590/1982-0224-20150178

ABSTRACT We tested whether interindividual variations in diet composition within a population of Deuterodon stigmaturus can be explained by morphological differences between individuals, and whether diet-morphology relationships are dependent on the ontogenetic development. We analyzed diet of 75 specimens sampled in a coastal stream of Southern Brazil. Variation in stomach content was summarized with a Principal Coordinate Analysis (PCoA). The retained PCoA axes were tested as response to standard length (SL), and to values of intestine length (IL) and mouth length (ML) independent of body size, using linear mixed-effects models (LMM). The most consumed food items by D. stigmaturus were filamentous algae (41%), terrestrial plants (20.3%), detritus (12%), and aquatic invertebrates (8.8%). The LMMs showed that SL was positively related to consumption of terrestrial plants, whereas IL independent of SL was negatively related to aquatic invertebrates and positively related to filamentous algae. When body sized was held constant, ML was not related to diet variation. Interindividual diet differences conditioned to body size suggest that individuals shift their trophic niche and function in the ecosystem along the ontogenetic development. Relationships between intestine length and diet composition suggest interindividual differences in foraging ability and digestibility of distinct food items. RESUMO Nós testamos se variações na composição da dieta de uma população de Deuterodon stigmaturus podem ser explicadas por diferenças morfológicas entre indivíduos, e se as relações entre morfologia e dieta são dependentes do desenvolvimento ontogenético. A dieta de 75 indivíduos amostrados em um riacho costeiro do sul do Brasil foi analisada. Uma Análise de Coordenadas Principais (PCoA) foi utilizada para sumarizar variações individuais no conteúdo estomacal. Os eixos retidos da PCoA foram testados como resposta ao comprimento padrão (CP) e ao comprimentos do intestino (CI) e da boca (CB), independentes do tamanho corporal, usando modelos lineares mistos (LMMs). Os itens macroscópicos mais consumidos por D. stigmaturus foram algas filamentosas (41%), plantas terrestres (20,3%), detritos (12%), e invertebrados terrestres (8,8%). Os LMMs mostraram que o CP foi positivamente relacionado ao consumo de plantas terrestres, enquanto que valores de CI independentes de CP foram negativamente relacionados ao consumo de invertebrados aquáticos e positivamente relacionados ao consu